US7729079B1 - Disk drive estimating fly height using a PLL tuned by a fly height capacitance - Google Patents
Disk drive estimating fly height using a PLL tuned by a fly height capacitance Download PDFInfo
- Publication number
- US7729079B1 US7729079B1 US12/356,701 US35670109A US7729079B1 US 7729079 B1 US7729079 B1 US 7729079B1 US 35670109 A US35670109 A US 35670109A US 7729079 B1 US7729079 B1 US 7729079B1
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- fly height
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- head
- oscillating signal
- disk drive
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- 230000005540 biological transmission Effects 0.000 claims description 32
- 239000003990 capacitor Substances 0.000 claims description 22
- 238000000034 method Methods 0.000 claims description 17
- 230000035945 sensitivity Effects 0.000 claims description 2
- 230000008878 coupling Effects 0.000 claims 4
- 238000010168 coupling process Methods 0.000 claims 4
- 238000005859 coupling reaction Methods 0.000 claims 4
- 238000001914 filtration Methods 0.000 claims 1
- 238000010586 diagram Methods 0.000 description 2
- 230000007613 environmental effect Effects 0.000 description 2
- 230000001939 inductive effect Effects 0.000 description 2
- 239000004065 semiconductor Substances 0.000 description 2
- 238000001514 detection method Methods 0.000 description 1
- 239000013643 reference control Substances 0.000 description 1
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Classifications
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- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
- G11B5/6011—Control of flying height
- G11B5/6064—Control of flying height using air pressure
-
- G—PHYSICS
- G11—INFORMATION STORAGE
- G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
- G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
- G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
- G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
- G11B5/60—Fluid-dynamic spacing of heads from record-carriers
- G11B5/6005—Specially adapted for spacing from a rotating disc using a fluid cushion
Definitions
- the impedance of the transmission lines may vary with changes in environmental conditions, such as with changes in temperature, altitude, and/or humidity. These impedance changes may affect the phase and/or magnitude response of the second oscillating signal 20 , thereby inducing an error in the FHE 38 A or 38 B. In one embodiment, changes in environmental conditions may be detected and the FHE adjusted accordingly. In another embodiment shown in FIG. 5A , a filter 59 is inserted into the transmission path which may help desensitize the FHE 38 to changes in impedance along the transmission lines so that the FHE is affected mainly by changes in the fly height capacitance.
- FIG. 2A employs a phase detector 22 for detecting a phase difference between the first oscillating signal 18 and the second oscillating signal 20 to tune the PLL 8 and generate the FHE 38 .
- a magnitude detector may be employed for detecting a magnitude difference between the first oscillating signal 18 and the second oscillating signal 20 to tune the PLL 8 and generate the FHE 38 .
- a combination of phase and magnitude detection may be employed in order to tune the PLL 8 and generate the FHE 38 .
- control circuitry may be implemented within a read channel integrated circuit, or in a component separate from the read channel, such as a disk controller, or certain steps described above may be performed by a read channel and others by a disk controller.
- the read channel and disk controller are implemented as separate integrated circuits, and in an alternative embodiment they are fabricated into a single integrated circuit or system on a chip (SOC).
- the control circuitry may include a suitable preamp circuit implemented as a separate integrated circuit, integrated into the read channel or disk controller circuit, or integrated into an SOC.
- control circuitry comprises a microprocessor executing instructions, the instructions being operable to cause the microprocessor to perform the steps of the flow diagrams described herein.
- the instructions may be stored in any computer-readable medium. In one embodiment, they may be stored on a non-volatile semiconductor memory external to the microprocessor, or integrated with the microprocessor in a SOC. In another embodiment, the instructions are stored on the disk and read into a volatile semiconductor memory when the disk drive is powered on. In yet another embodiment, the control circuitry comprises suitable logic circuitry, such as state machine circuitry.
Abstract
Description
Claims (28)
Priority Applications (1)
Application Number | Priority Date | Filing Date | Title |
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US12/356,701 US7729079B1 (en) | 2009-01-21 | 2009-01-21 | Disk drive estimating fly height using a PLL tuned by a fly height capacitance |
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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US12/356,701 US7729079B1 (en) | 2009-01-21 | 2009-01-21 | Disk drive estimating fly height using a PLL tuned by a fly height capacitance |
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US7729079B1 true US7729079B1 (en) | 2010-06-01 |
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US12/356,701 Active US7729079B1 (en) | 2009-01-21 | 2009-01-21 | Disk drive estimating fly height using a PLL tuned by a fly height capacitance |
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Cited By (118)
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